Studies of autoignition-assisted nonpremixed cool flames

Murakami, Yuki; Reuter, Christopher B.; Yehia, Omar R.; Ju, Yiguang

doi:10.1016/j.proci.2020.06.379

Cited by 8 publications

(4 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Diethyl ether (DEE, C 4 H 10 O) was proposed as a promising biofuel for internal combustion engines . DEE oxidation was experimentally investigated in the past several decades, including factors such as ignition delay time, − laminar flame speed, − extinction limit, , and species measurement in laminar flow reactors, jet-stirred reactors, − and burners. , Table summarizes the recent experimental studies for DEE oxidation at different temperatures ( T ), pressures ( P ), equivalence ratios (ϕ), and residence times (τ). However, the experimental data is still lacking for DEE low-temperature oxidation at high pressure (above 10 atm).…”

Section: Introductionmentioning

confidence: 99%

Study of Low- and Intermediate-Temperature Oxidation Kinetics of Diethyl Ether in a Supercritical Pressure Jet-Stirred Reactor

et al. 2023

Self Cite

View full text Add to dashboard Cite

Growing demand for low-emission and high-efficiency propulsion systems spurs interest in understanding low-temperature and ultra-high-pressure combustion of alternative biofuels like diethyl ether (DEE). In this study, DEE oxidation experiments are performed at 10 and 100 atm, over a temperature range of 400−900 K, at fuel-lean, stoichiometric, and fuel-rich conditions by using a supercritical pressure jet-stirred reactor (SP-JSR). The experimental data show that DEE is very reactive and exhibits an uncommon low-temperature oxidation behavior with two negative temperature coefficient (NTC) zones. The first NTC zone is mainly governed by the competition reactions of QOOH + O 2 = O 2 QOOH and QOOH = 2CH 3 CHO + OH, while the second one is mainly governed by the competition reactions of R + O 2 = RO 2 and the β-scission reaction of fuel radical R. It is shown that the increase of pressure stabilizes RO 2 and promotes HO 2 chemistry. Moreover, the branching ratios of β-scission reactions of R and QOOH decrease. As a result, it is shown that, with the increase of pressure, both NTC zones become weaker at 100 atm. In addition, the intermediate-temperature oxidation is shifted considerably to lower temperature at 100 atm. The existing DEE model in the literature well predicts the experimental data at low temperature; however, it underpredicts the fuel consumptions at intermediate temperature. The H 2 /O 2 subset in the existing DEE model is updated in this study based on the Princeton updated HP-Mech, including the singlet/triplet competing channels of HO 2 related reactions. The updated model improves the overall predictability of key species, especially at intermediate temperature.

show abstract

Section: Introductionmentioning

confidence: 99%

Study of Low- and Intermediate-Temperature Oxidation Kinetics of Diethyl Ether in a Supercritical Pressure Jet-Stirred Reactor

et al. 2023

Self Cite

View full text Add to dashboard Cite

show abstract

“…The development of these new-concept combustion techniques depends on a deep understanding of fuel's low-temperature oxidation kinetics, which has received increasing research attention recently. Low-temperature chemistry has been proven to have a significant impact on the engine's ignition, knock and combustion efficiency [7][8][9][10]. For instance, low-temperature chemistry is dominant for auto-ignition propensity, which in turn is related to the engine knock or super-knock phenomena [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Effects of Carbon Chain Length on N-Alkane Counterflow Cool Flames: A Kinetic Analysis

Tian

Liu

2022

Fire

View full text Add to dashboard Cite

An in-depth understanding of the low-temperature reactivity of hydrocarbon fuels is of practical relevance to developing advanced low-temperature combustion techniques. The present study aims to study the low-temperature chemistry of several large n-alkanes with different carbon chain lengths in counterflow cool diffusion flames by kinetic analysis. The large n-alkanes that were chosen are n-heptane (NC7H16), n-decane (NC10H22) and n-dodecane (NC12H26), which are important components of practical fuels. Firstly, the thermochemical structure of a typical cool diffusion flame is understood through its comparison with that of a hot diffusion flame. The boundary conditions, including the ozone concentration, fuel concentration and flow velocity—where cool flames can be established—are identified with a detailed chemical mechanism that evaluates the low-temperature reactivity of the investigated n-alkanes. The results show that the n-alkane with a longer carbon chain length is more reactive than the smaller one, thereby indicating the order of NC12H26 > NC10H22 > NC7H16. This trend is qualitatively similar to the findings from non-flame reactors. The reaction pathway and sensitivity analysis are performed to understand the effects of carbon chain length on the low-temperature reactivity. The contribution of an n-alkane with a longer carbon chain to the dehydrogenation reaction, oxidation reaction and isomerization reaction is greater than that of a smaller n-alkane, and abundant O and OH radicals are generated to promote the fuel low-temperature oxidation process, thereby resulting in an enhanced low-temperature reactivity. The effects of ozone addition on the low-temperature reactivity of n-alkanes are also highlighted. It is found that the addition of ozone could provide a large number of active O radicals, which dehydrogenate with the fuels to generate OH radicals and then promote fuel low-temperature oxidation. The present results are expected to enrich the understanding of the low-temperature characteristics of large n-alkanes.

show abstract

“…The existence of counterflow cool diffusion flames was predicted by Law and coworkers [10,22]. These flames were subsequently observed in normal gravity for nbutane, iso-butane, n-heptane, n-octane, n-decane, n-dodecane, n-tetradecane, dimethyl ether, and diethyl ether at various pressures [5,12,[23][24][25][26]. Owing to the short residence times available in counterflow flames, they required LTC enhancements such as heated reactants, pulsed plasmas, and ozone addition [5,23].…”

mentioning

confidence: 96%

“…Cool diffusion turbulent flames were investigated experimentally and numerically for dimethyl ether in a jet flame configuration [31]. Auto-ignition assisted turbulent cool diffusion flames were studied for diethyl ether in the same jet flame configuration [26].…”

mentioning

confidence: 99%